Update introduction in README

The introduction only mentioned the chrome dev tools which left the impression that there is no version for other browsers. Thus, the text has been updated.
Merge pull request #98 from fbender/patch-1

Update introduction in README
FIX: workaround firebug console.debug/console.log exception
Merge pull request #95 from rpl/fix/firebug-console-exception

FIX: workaround firebug console.debug/console.log exception
Bump version patch to 0.0.6
Update mozilla addon sdk to 1.15 and bump version patch to 0.0.7